1. Field of the Invention
The present invention relates to a manufacturing apparatus of a semiconductor device having a circuit including a thin film transistor (hereinafter called a TFT), and a manufacturing method of the semiconductor device. For example, the present invention relates to an electronic device in which an electro-optical device typified by a liquid crystal display panel or a light-emitting display device having an organic light-emitting element is mounted as parts thereof.
In this specification, the semiconductor device refers to general devices that can function by using semiconductor characteristics, and an electro-optical device, a semiconductor circuit, and an electronic device are all included in the semiconductor device.
2. Description of the Related Art
In recent years, attention has been focused on a technique for forming a thin film transistor (TFT) using a semiconductor thin film (with a thickness of about several nanometers to several hundred nanometers) formed over a substrate having an insulating surface. Thin film transistors are widely applied to electronic devices such as an IC and an electro-optical device. In particular, development is urgently required on thin film transistors as switching elements of image display devices.
In general, a lithography technique is used for processing a thin film formed over a substrate having an insulating surface. In a process using a lithography technique, a thin film is processed through a series of steps such as a resist coating step, a resist exposure step using a photomask, a resist development step, an etching step using a resist pattern, and a resist removal step. Therefore, the process using a lithography technique takes up many steps and time, which causes an increase in production cost. For example, when a TFT or the like using amorphous silicon is manufactured, the process using a lithography technique is performed five times, and five different photomasks are required.
In addition, for a photomask used for a lithography technique, a light transmitting base material having a small linear expansion coefficient and a small change depending on humidity, specifically glass or quartz, is used, and a fine mask pattern is formed of a light shielding material over the light transmitting base material. Although light exposure using this photomask can realize a high-precision resist pattern, there is a problem in that the production cost of the photomask is very expensive. Since the amount of time required for photomask production is long, a photomask has disadvantages in a field in which a product development cycle is desired to be short. In addition, with a conventional photomask, only one kind of pattern can be formed. Further, even when a small part of photomask design is desired to be changed, it is difficult to shorten the amount of time required for photomask production.
In addition, when mass production of semiconductor devices is carried out, a method for reducing the production cost by increasing a substrate area is taken. However, when the size of the photomask is increased, the production cost of the photomask is also increased.
Further, a stepper is a very expensive apparatus. The larger the stepper is, the more expensive it is. In the case of using a large-sized substrate, a complex optical system is necessary, and a footprint occupied by an exposure apparatus is increased.
In a resist coating step and a resist development step, a large amount of waste liquid is generated. It is necessary to provide piping for carrying the large amount of waste liquid generated in this manner, and a tank for storing thereof. In addition, since a resist material is easily deteriorated, it is difficult to perform material quality control for always using a fresh resist material in a process.
In this manner, when mass production of semiconductor devices is carried out, even when a substrate area is increased to reduce production cost, there are problems in that the amount of capital investment increases and the number of steps increases in the case of using a lithography technique in a manufacturing process.
The assignee of this application has described a method for processing a thin film to form an opening, in which a laser beam having a wavelength of less than or equal to 400 nm is used, and a light transmitting conductive film is irradiated with a linear beam, in Reference 1: U.S. Pat. No. 4,861,964, Reference 2: U.S. Pat. No. 5,708,252, and Reference 3: U.S. Pat. No. 6,149,988.